<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <h1>首页</h1>
    <% if(username){ %>
        <span><%=username%></span>
        <a href="/center">个人中心</a>
        <a href="/logout">退出登录</a>
    <% }else{ %>
        <a href="/login">登录</a>
    <%}%>
</body>
</html>